English

Abstract

Stress analysis plays important role in the structural integrity and optimization. Prior stress estimation helps in better design of the products. Composites find wide usage in the industrial and home applications due to its strength to weight ratio. Especially in the air craft industry, the usage of composites is more due to its advantages over the conventional materials. Composites are mainly made of orthotropic materials having unequal strength in the different directions. Composite materials has the drawback of delamination and debonding due to the weaker bond materials compared to the parent materials. So proper analysis should be done to the composite joints before using it in the practical conditions. In the present work, a composite plate with elastic pin is considered for analysis using finite element software Ansys. Initially the geometry is built using Ansys software using top down approach with different Boolean operations. The modeled object is meshed with 3 dimensional layered element solid46 for composite plate and structural three dimensional solid element Solid45 for pin material. Various combinations are considered to find the strength of the composite joint under uniaxial loading conditions. Due to symmetry of the problem, only quarter geometry is built and results are presented for full model using Ansys expansion options. The results show effect of pin diameter on the joint strength. Here the deflection and load sharing of the pin is increasing and other parameters like overall stress, pin stress and contact pressure is reducing due to lesser load on the plate material. Further material effect shows, higher young modulus material has little deflection, but other parameters are increasing. Interference analysis shows increasing of overall stress, pin stress, contact stress along with pin bearing load. This increase should be understood properly for increasing the load carrying capacity of the joint. Generally every structure is preloaded to increase the compressive stress in the joint to increase the load carrying capacity. But the stress increase should be properly analysed for composite due to its delamination and debonding effects due to failure of the bond materials. When results for an isotropic combination is compared with composite joint, isotropic joint shows uniformity of the results with lesser values for all parameters. This is mainly due to applied layer angle combinations. All the results are represented with necessasary pictorial plots. . In this section, we examine the problem of composite laminates with an elastically pinned circular hole. The effects of friction and bearing load on the stress redistribution are studied in detail, based on the infinite plate configuration. The issues of practical interest, such as the loading-history and cycling dependencies of stress state due to the presence of friction, are addressed. The material properties and the numerical meshes used in the simulation are described below. The laminate plate contains seven plies of identical orthotropic material with the stacking sequence (0/±45/90ˉ)s. The orthotropic material represents a unidirectional fiber-reinforced composite plate. With the fibers lying in the horizontal plane (Lubin, 1982). The number in the stacking sequence indicates the in-plane rotation angle of each ply relative to the reference 0 o -ply where the fibers lie in the 0 o direction. The elastic constants are given by E1=138 GPa, E2 = E3 =14.5 GPa, μ23= μ13= μ12=5.86 GPa, and ν23=ν13=ν12=0.21. Meanwhile, the isotropic pin is made of Ti-6Al-4V, and the